Problem: Evaluate $0.1m+8-12n$ when $m=30$ and $n=\dfrac14$.
Let's substitute $ m= {30}$ and $ n={\dfrac14}$ into the expression. $\phantom{=}0.1 {m} +8-12{n}$ $=0.1( {30}) +8-12\left({\dfrac14}\right)$ $=3+8-3$ $=8$